Surface energy represents the excess energy that is present at the surface of a material as compared to the whole material. When a solid body is cut into two pieces, its bonds get disrupted and the surface area increases. As a result, the surface energy also increases. Surface energy can be determined by measuring it with contact angle experiments. In this method, the contact angle of liquids, such as water and diiodomethane, is measured with the surface and surface energy is calculated on the basis of surface tension and contact angle. Surface energy can also be determined by calculating the surface energy of a deformed solid and by calculating the surface formation energy of a crystalline solid. This book covers in detail some existent theories and innovative concepts revolving around surface energy. It is an upcoming field of science that has undergone rapid development over the past few decades. For someone with an interest and eye for detail, this book covers the most significant topics in the field of surface energy.